Clutch mechanism



March l5, 1938. E. L. coNNELL CLUTCH MECHANISM Filed Nov. 9, 1933 2 Sheets-Sheet 1 vnlIllllllllllllllllll' Patented Mar. 15, 1938 UNITED STATES PATENT OFFICE 35 Claims.

'Ihis invention relates to clutch mechanisms and particularly to clutch mechanisms adaptable for use in power operated tools.

It is an object of the invention to provide an improved clutch mechanism for transmitting power from a driving to a driven machine element.

Another object is to provide a clutch mechanism having improved releasing means whereby when the load transmitted by the clutch from a driving to a driven element exceeds a predetermined value the clutch may automatically be released to break the driving connection from the driven element.

Another object is to provide such a clutch l5 mechanism having improved adjusting means for adjusting the predetermined value at which the clutch automatically releases.

Another object is to provide, in a power transmitting clutch mechanism of the type employing a helical spring, an improved mounting and associated elements for the spring.

Another object is to provide a rotary power transmitting clutch mechanism through which power in alternate directions may be transmitted.

Another object is to provide an improved rotary power transmitting clutch mechanism which may be reversed to transmit rotary power in alternate directions and in at least one oi which directions the clutch is automaticallyreleasable upon' the attainment of transmitted torque above a predetermined value.

Another object is to provide a clutch mechanism particularly adaptable to portable power driven tools such as tools for screwing on nuts or the like and for unscrewing the same, and when operating in the screwing-0n direction, having automatic releasing means to release the application of power when the applied torque reaches a predetermined value, and whereby torque may be applied directly from the power means in the screwing-on direction independently of the release means.

Other objects will be apparent to those skilled in the art to which my invention appertains.

My invention is fully disclosed inthe following description taken in connection with the accompanying drawings, in which:

Fig. l is a side longitudinal sectional view of a portable tool of the motor driven type illustrating an embodiment of my invention `applied thereto;

. Fig. 2 is a partly sectional partly elevational View of the embodiment of Fig. l taken from a plane at right angles to the sectional plane of that ligure;

Fig. 3 is a transverse sectional view taken from the plane 33 of Fig. l.

Fig. 4 is a view generally similar to Fig. l but illustrating a modication;

Fig. 5 is a cross-sectional view taken from the plane 5-5 of Fig. 4; and,

Fig. 6 is a view similar to Fig. l but illustrating a further modification.

Referring to the drawings, I have shown at I the external housingfof a motor which has been broken apart transversely to shorten it longitudinally to clarify the drawings, the housing terminating upwardly in a pistol grip handle 2 to which an electric current supplying cord 3 is secured and adjacent to which a trigger type switch 4 is disposed, whereby upon gripping the handle 2 an operator may, with his finger, actuate the trigger 4 to close a circuit from the wire 3 to start the motor in the housing I.

By means of the handle 2 also the operator may depress downwardly upon the tool as a whole to suitably apply pressure upon the work in a manner' to be described, by which, in a manner to be described, the clutch mechanism of my invention may be actuated.

The motor housing I has in the lower portion thereof a housing 5 upon the lower end of which is secured a downwardly projecting tubular housing 6 secured to theA housing 5 by a flange 1 and suitable bolts projected therethrough.

A ballvbearing shown generally at has an outer raceway 9 fitted into a suitable bore in the lower part of the housing 5 and the inner raceway II] thereof is pressed upon a spindle II engaging a shoulder I2 thereon; a driving clutch member I3 is keyed to the spindle I I to be driven thereby and is press-fitted on the lower end of the spindle II to clamp the inner raceway Ill against the shoulder I2.

Upon the spindle Il above the raceway I0 is keyed a gear I4 meshed with a pinion I5, the latter having a shaft I6 connected to the motor (not shown) in the housing I; and by this means the driving clutch member I3 may be rotatably driven by the motor.

A second inner raceway IU is pressed upon the spindle II above the gear I4 and a cooperating outer raceway 9 is pressed into a suitable bore in `the housing 5. Thus the spindle II and clutch member I3 are rotatably supported as a unit on the housing through the ball bearings.

The tubular housing 6 has a bore coaxial with the spindle II, lined withy a bearing sleeve I'I in which is rotatably fitted the driven clutch member IB and drivenl head I9, these parts being formed outwardly with cylindrical surfaces fitting the bore of the sleeve |1.

The lower surface of the driving clutch member |3 is provided with a plurality, such as three. depending lugs or jaws 26-26, and the upper portion of the driven clutch member i8 is similarly provided with lugs or jaws 2 |2|, the outer axial ends of the respective lugs or jaws being spaced from each other as shown at 22; but in the operation to be described, the jaws 2| may be moved axially and be overlapped with the lugs 20 to effect driving engagement therethrough.

The bearing sleeve I1 has on its inner end an outwardly extending flange 23 overlapping a shoulder on the tubular housing 6. The driven clutch member i6 has a. corresponding flange 24 overlapping the flange 23. By this means the rotatable driven clutch member I6 is prevented from moving axially outwardly from the tubular housing 6.

A rotary shaft 25 extends axially through the mechanism thus far described and on a lower portion projecting out of the housing 6 is enlarged as at 26 to provide a head and to provide a shoulder 21. The head I9 is generally tubular, the lower end of which is closed by a relatively thickened portion 28 which also is keyed as at 28 to the head 26 of the shaft to rotate therewith and to move axially therewith bodily.

The upper portion 38 of the shaft 25 is of reduced diameter and is rotatable in a bore 3| of the spindle Above the end 30 of the shaft, and in the bore 3|, is disposed a helical compression spring 32 having secured in one end thereof a rounded button 33 engaging the shaft extreme upper end portion 38 and the other end of the spring abutting upon the bottom of the bore 3|. The spring 32 thus exerts constantly downward thrust on the shaft 25, whereby as will presently be understood, the clutch jaws 20 and 2| are normally disengaged by downward axial movement of the shaft effected by the spring 32. The button form of the device 33 reduces to a negligible amount friction occasioned by relative rotation of the shaft and spindle Il.

The upper side of the driven clutch member i8 is recessed as shown at 35 and in the recess is disposed a ratchet head 36 having a central axially extending bore 31, hexagonal in cross-section, whereby it may be drivingly associated with the shaft 25 by fitting upon a corresponding hexagonal portion 31 of the shaft. The lower side of the ratchet head 36 engages a shoulder 38 on an adjacent portion of the shaft 25 and is restrained from movement away from the shoulder by a split ring 35 seated in a shallow groove 40 in the shaft and overlapping adjacent portions of the ratchet head 36. 'Ihe split ring 39 may be retained in closed shaft gripping condition by a wire 4i circumscribing the same. The ratchet head 36 is thus rigidly secured against axial movement on the shaft. The lower side of the ratchet head 36 rests upon the balls 42 of a thrust ball bearing which in turn is seated in a recess 43 in the driven clutch element I8.

In the structure to be described, a spring 6 5 exerts thrust axially tending to move the clutch element I8 vertically (as viewed in Fig. 1) with respect to the shaft 25, and the thrust ball bearing comprising the balls 42 engaging the lower side of the ratchet head 36 on the shaft and the upper side of the recess 43 of the clutch element, absorbs this thrust substantially without friction.

The ratchet head 36 may be of a well known construction having wedge-shaped lateral faces 44 between which and the wall of the recess 35, rollers 45 are disposed resiliently pressed toward the narrow end of the wedge-shaped space 46 thus provided by compression springs 41. As is well known, upon rotation of the driven clutch` is disposed in the recess locked in position against outward movement by an annular split ring 49 seated in a corresponding groove in the side of the recess.

The lower portion of the driven clutch element I8 is of reduced diameter as at 50 and fits into the inner cylindrical bore of the tubular driven head I9 at the upper end thereof, and within the head i9 has its lower axial end of helicoidal form as shown at 5|, Fig. 2, providing a shoulder 52 whereby it completely ts the u'pper end of a helical spring 53, closely wound and preferably formed from metal rectangular in cross-section whereby to provide an outer cylindrical surface 54 of diameter substantially the same but preferably slightly less than the diameter of the bore 55 of the tubular driven head i9.

The lower end of the spring 53 is fitted upon a shoulder 56 and upon inclined helicoidal surfaces 51-51 of an intermediate driving clutch element 58 externally cylindrical and axially movable in the bore 55, and having on its lower surface a plurality, preferably two, outwardly extending lugs or jaws 59 adapted upon relative rotary movement to engage a corresponding pair of lugs or jaws 60 projecting upwardly from a ring form intermediate driven clutch element 6| which has outwardly radially extending splines 62-62 projected into vertically disposed spline slots 63-63 in the wall of the tubular driven head I9.

A spring housing 64 in the general form of an elongated cup has its cup skirt surrounding and coaxial with the shaft 25 but spaced therefrom to provide space for helically wound compression spring 65 to be disposed within the cup skirt and around the shaft 25; and the lower or open end of the cup skirt is exteriorly threaded as at 66 and upon the threads thereof is threaded a nut 61 centered with a cylindrical bore 68 of the ring form intermediate driven clutch element 6| by a reduced diameter neck portion 69 projected into said bore. 'I'he shoulder 10 thus provided engages the lower side of the ring form intermediate driven clutch element 6| to support it.

The nut 61 and cup 64 are in turn resiliently supported by the spring 65 abutting at one end upon the shoulder 21 and at the other end upon the cup bottom 1| interiorly thereof, the cup bottorn being correspondingly perforated to allow the shaft 25 to extend slidingly therethrough.

Preferably a key 12 is interposed between the upper end of the spring and the cup bottom 1| and may, as shown, be formed from a piece of round wire partly circumscribing the shaft 25 and having an inwardly radially extending end 13 projected into a longitudinally extending keyway 14 in the shaft 25 and having its opposite end 15 bent into the axial direction and projected into a suitable perforation, not shown, in the cup bottom 1| By this arrangement, 'the cup is keyed to the shaft against rotation but is permitted to move axially thereof.

The lateral faces of the lugs I8 and III, for example the face 16 ot the lug 5l, are inclined at a predetermined angle for a reason to be explained.

'I'he helical spring 53, which as will be understood, is interiorly cylindrical, is lined by a cylindrical bushing 11 of metal which may extend from the driven clutch member I8 to the intermediate driving clutch element 58 and closely fits the inner wall of the spring.

In the operation of this spring to be described, the bushing assists in aligning the spring axially and disposing it so that when it is expanded to engage the cylindrical bore 55, it will engage the same more uniformly on successive operations and with greater eillciency as a gripping clutch element and will continue to operate over a greater length of time without deterioration than in prior devices of this general class where such helical springs are employed generally as a clutch element.

The head 26 or lower end of the shaft is, as above stated, projected through and keyed against rotation in the thickened transverse portion 29 of the driven head I9 and may have an enlarged diameter portion 18 providing a shoulder 19 engaging the lower end of the said head I9. Below the head I9 the shaft is provided with a chuck 80 of any known or suitable construction adapted to vgrip the Shanks, suchas 8|, of various tools such as the nut or screw head receiving wrench 82 of Fig. 2.

Myl invention has been illustrated and described in the foregoing as embodied in a motor operated portable hand tool for screwing in cap screws and the like or screwing on nuts on bolts etc., and I have chosen this embodiment for illustration and description herein inasmuch as this is one of the particular uses of my invention.

The mode of operation of the foregoing embodiment is as follows: The operator grasps the tool handle 2 in one hand and grips the housing 6 in his other hand and presents the tool such asthe wrench tool 82 to the work, for example to the head of a cap screw 83 as illustrated. Upon depressing the tool as thus held, the entire assembly including the shaft and driven head I9, driven clutch member I8, intermediate driving clutch element 5B, and intermediate driven clutch element 6I will thereby be moved relatively upwardly within the tubular housing Ii (or the latter will be moved downwardly thereover). This will bring into engagement the clutch jaws 2li-2 I. At this time power may be applied to the driving clutch member I3 through the gears I5 and I4 from a motor in the housing I, the curren't to the motor being supplied through the wires 3 andunder the control of the trigger-form switch 4.

The switch which is not shown but which may be of any known or suitable construction,v and enclosed within the handle 2, is preferably of the V4 reversing switch type; that is to say, when the trigger 4 is moved in one direction, the motor will be energized to turn in one direction, and when the trigger 4 is moved in the other direction the motor will be reversed in direction.

It will be assumed that when the motor was started as above referred to, it will rotate the shaft 25 in the clockwise direction as viewed from above.

The torque transmitted through the jaws 20 and 2| will turn the driven clutch member I8,

and,by virtue of the shoulder 52 thereof will transmit torque to the upper end of the helical spring 53. The resistance ofthe load tends to hold stationary the shaft head 26 and head I9 and therefore tends to hold stationary the ring form intermediate driven clutch element II by virtue of the splines 82 thereof engaged with the slots 88; and this in turn will tend to hold stationary the intermediate driving clutch element 58. 'I'he tendency to hold the intermediate driving clutch element 58 will, due to the reaction of the lower end of the helical spring 53 upon the shoulder 56, cause the spring to exert a torque upon the said stationary parts to drive the load and turn the screw 83 into the work. If, however, the load of turning the screw is above that necessary to unwind the spring 53 however slightly, it will unwind and thereby expand and will grip the bore of the driven head I9 and thereafter will drive the head I9 by this frictional engagement of the cylindrical wall of the spring 53 and that of the head I9.

It will be observed that the spring is kept in its expanded condition and driving engagement by the pressure of the lower end of the spring upon the shoulder 56. This pressure, as will now be apparent, is transmitted through the slots 53, splines 62, intermediate driven clutch element 6I and through the inclined jaw faces I6-16 to the intermediate driving clutch element 58.

If now the load of running in the screw 83 should reach a predetermined value such as that occurring when the head of the screw is forced home, the load transmitted through the inclined faces 1B, which are of predetermined inclined angle, will be sufdcient to cause them to slide over each other and cause the intermediate driven clutch element 6I to be moved downwardly until the jaws can slide over the jaws 59. The spring expanding torque is thereby released and the spring 53 contracts slightly and slips in the bore 55 permitting it and the intermediate driving clutch element 58 to rotate. A half revolution later, the lugs 59 will engage the lugs 60 again, and if the predetermined load is still present, they will again force the clutch element 6I downwardly and ride thereover. Thus,at the attainment of said load, the clutch is released `and it will be indicated to the operator by the periodic clicking and jumping of the clutch element 6I over the teeth 59 of the clutch element 58.

The predetermined load may be adjustably varied by screwing the nut 61 up or down to vary the tension of the spring 65 which is the spring which holds, resiliently, the clutch element 5I upwardly against the clutch element 58, and supplies the force to hold the inclined teeth 59 and 68 inengagement. Obviously, screwing the nut 61 to pull the cup skirt 64 downwardly, will increase the tension of the spring 65 and raise the releasing or tripping clutch load.

Dtu'ing this operation the relatively small axial thrust to hold the wrench 82 to its work is taken upwardly on the ball bearing B-IU. When the clutch begins toslip or is released as above described, the operator may remove the wrench preparatory to applying it to another screw.

When it is desired to unscrew a bolt or remove a nut, the tool 82 is presented to the head or to the nut as illustrated in Fig. 2 and the switch 4 is thrown to the reverse position. Thereupon the driving clutch member I3 is rotated counterclockwise as viewed from above. Now upon depressing the tool to engage the clutch jaws III-2|, the driven clutch member I8, Fig.. 3, is rotated in the clockwise direction. This causes the rollers 45 to move toward the apex of the wedge-shape spaces 46 to effect a clutch grip between the ratchet head 36 and the inner wall of the recess 35 of the driven clutch member I8 to lock these two members together. This locks the axially disposed shaft 25 with the driven clutch member I8 and rotates the shaft positively in the reverse direction from that above described.

The full torque of the motor is supplied directly to the shaft to loosen the nut or the screw and continued rotation thereof will remove it. In either case, vupon removing the tool from the work, the spring 32 will expand and shove the shaft downwardly and disengage the clutch jaws 20-2I whereby, although the motor may be continued in movement, the tool will stop rotating in order that it may conveniently be presented to the work. y

In order to nx the releasing load adjustment, any suitable means may be provided to prevent the nut 61 from changing its position on the threads 66. The preferred means is to form a shallow groove 85 in the outer generally cylindrical wall of the head I9 and to place therein a fiat circular spring 86 having at one side of the circle an inwardly projecting nger 81 and providing on the periphery of the nut 61 a series of teeth 88 engageable by the finger 81. The annu lar spring 86 may be secured against rotation in its groove 85 in any suitable manner, and the finger 81 may be removed outwardly radially from its engaged tooth 88 to permit rotating the nut to change the adjustment.

According to the above description of the construction and mode of operation it will be observed that power applied to the driven clutch member I8 is transmitted through the spring 53 to the ring form intermediate driven clutch element 6|; and that the clutch element 6| alone will rotatively drive the head I9 and the tool thereon if the torque load is below a certain minimum; and that if the load rises above this minimum, then some of the torque applied to the spring 53 will be transmitted directly into the head I8 and a relatively small fraction of the torque will be transmitted to the clutch element 6I and thence to the head I9. As the load torque becomes greater and greater, the portion of the load transmitted to and through the clutch element 6| becomes greater; and if the total torque load reaches a certain maximum, the portion carried by the clutch element will be sufficient to cause it to slip, whereupon the transmission of driving torque from the spring directly to the head ceases, and the ring being unable alone to drive the head and its load, the head and its tool load stop rotating.

When the motor is reversed and the power is applied directly through the ratchet head 36 to the shaft, torque may be applied to the tool 83l up to the full capacity o f the motor, there being no provision for slipping at maximum load in that direction of rotation.

Obviously, it is desirable that when the motor is applying power through the slippable clutch elements 58 and 6| the tool will rotate in the direction to screw nuts on and to screw screws in because it is desirable that the clutch shall slip when the head of the screw or when the nut jams upon the work, and therefore when the motor is reversed to remove a nut or the like the full power of the motor will be available to start lt without the possibility of any slippage occurring in the clutch.

It will be observed that the splines 52-62 projecting into the vertical slots $3, constitute a spline connection preventing relative rotary but permitting relative axial movement. Obviously, other forms of spline connection may be employed for this purpose.

The maximum load at which the clutch element 6I slips and therefore the load at which the clutch device as a whole stops transmission, while adjustable by the spring 65, is primarily determined by the slope of the cam face 16 on the lug 58 or on the corresponding faces of the lugs 60.

Thus the range of adjustment ofthe spring 65 may be changed as desired by changing the slope of the said cam faces.

In the form of my invention illustrated in Figs. 4 and 5, a helical spring |00 is expanded to engage the inner cylindrical surface |I on a tubular upper portion |02 of a driven head |03 to drive the driven head in one direction, say, clockwise when viewed from above, and the same helical spring |00 may be contracted to grip directly the shaft |04 to rotate it and the driven head in the other direction. 'I'he structure by which this is accomplished will now be described.

In this form a motor housing |05, a depending tubular guide 06 and a driving clutch member |01 and the bearing support and gear drive for the latter may be the same as the corresponding parts of the form of Fig. 1.

The driven clutch member |08 having upwardly projecting teeth or jaws |09 engageable with depending teeth or jaws |I0 on the driving clutch member, is normally supported by a flange I II overhanging the upper end of the liner I2 in the tubular frame member |06.

An axially extending downwardly open slot I I3 is provided in the driven clutch member |08 and in this slot is seated an end portion I|4 of the helical spring bent into the axial direction. By this means, rotation of the driven clutch member |08 in either direction will correspondingly tend to wind up or unwind the helical spring |00. The lower end of the helical spring 00 has a similar end portion I |5 bent in the axial direction and lodged in a corresponding slot IIB in the intermediate driving clutch element II 1 whereby tendency of the spring |00 to turn may be resisted in either direction of rotation. The lower portion of the intermediate driving clutch element I|1 is provided with two or more lugs or clutch teeth ||8 having inclined faces IIS and engageable, in alternate directions of rotation, with corresponding inclined faces |2I and |22 on a corresponding plurality of clutch teeth |23 on a ring form intermediate driven clutch element |24 having splines I25-I25 extending into generally axially disposed spline grooves or slots I26--I26 in the driven head |03.

The shaft |04 is keyed to the driven head |03 to rotate therewith as indicated at |21. A spring |28 exerts an upward thrust on the lower side of the ring form clutch element |24 to maintain the clutch teeth |23 and ||8 normally in engagement and the tension of the spring may be variably adjusted by means of a nut |28' threaded on the shaft |04 below the member |03, and a pin |29 in an axially extending bore |30 in the driven member |03, the lower end of the pin standing upon the. nut |28' and the upper end of the pin engaging the underside of a washer I3| which surrounds the shaft I 04 and upon which the spring |28 at its lower end abuts.

The upper surface of the nut |28' may be provided with a circular series of recesses |32 into which the end of the pin projectsQBy this means the nut |28' will be fixed in any rotated adjusted position. Upon turning the nut, the tension of the spring |28 may be suitably varied. Three such pins |29 may be provided if preferred as indicated in Fig. 5.

It will be observed that the upward thrust of the spring |28, transmitted through the clutch element |24, the clutch element I and the driven clutch member |08, tends to move the latter upwardly axially relative to the shaft |04; and to maintain the correct relation between these elements and take up this end thrust without undue friction, a ball bearing is provided comprising an outer race element |33 pressed into a suitable bore in the driven clutch member |08 and retained therein by an expanding split ring |34, and an inner race element |35 press-fitted upon the upper end of the shaft |04 and retained in position by a ring |36 having a spring Wire |31 surrounding the same, the rings |34 and |36 being seated in suitable annular recesses in the parts which they engage.

The upper end of the shaft |04 may project into an axial bore |38 in a spindle |39 and a spring |40 may be provided in the spindle in a manner vsimilar to and for the purposes of the corresponding parts more completely described in connection with Fig. 1. K

In the operation of the form of my invention of Figs. 4 and 5, upon presenting a tool 8| to a screw to be run in, the clutch jaws |09||0 of the driving and driven clutch members will be engaged by the upward movement of the shaft assembly as described for the form of Fig. 1, and torque will be transmitted from the driven clutch member through the spring, intermediate driving clutch element and through the jaws |23 and ||8 to the ring form intermediate driven clutch element |24, and thence through the splines I 25 and slots |26 to the driven head |03, and thence to the shaft |04 tending to turn it. Preferably this rotation will be in the clockwise direction as viewed from above and when the load reaches the predetermined value, the spring will tend to unwind and grip the surface |0| above referred to and thereafter the driven member will be driven through the spring and through the clutch element |24; and if the load reaches a predetermined maximum such as that attained when the screw is turned all the way home, the clutch tooth faces ||9 will move over the corresponding engaged faces |2| with a cam-like action compressing the spring |28 and thereafter so long as the load is present the shaft |04 will stand without rotation and the clutch teeth II8 will trip over the clutch teeth I 23 at each half revolution, where two pairs of said teeth are employed, thus releasing the clutch effect.

When the motor is rotated in the reverse direction as for example to loosen and remove a nut, a similar action takes place but the spring |00 tends to wind up and the faces |20 of the clutch teeth IIB engage the faces |22 of the clutch teeth |23. As the motor torque is applied tending to turn the shaft |04 in this counter-clockwise direction as viewed from above, the spring will contract and grip the shaft |04 therewithin and the shaft is to this end preferably provided with an enlarged diameter cylindrical portion |4I. Again, if the torque reaches a predetermined maximum at which it is desired that the clutch shall slip, the two faces |20 will cam over the faces |22, compressing the spring |28 and allowing the clutch to slip.

In this form of my invention it is apparent that the maximum torque load at which the clutch slips will be determined primarily by the inclination or angular slope of the clutch tooth faces- |I9|2| and |20-|22, and that this may be further secondarily adjustedby the spring |28. It will therefore` be apparent that the clutch tooth faces through which torque is applied to loosen a tight screw or nut may be of steeper inclination and therefore provide a greater maximum torque value than the other faces through which torque is applied to screw a nut on.

In the form of my invention of Fig. 6, I have shown a construction generally similar t'o that of Fig. 4, but adapted to the drill holding chuck of a drill press. To this end, the driving clutch member 200 is formed upon or secured to a taper shank 20| having a standard taper for gripping in a taper chuck. The driving clutchV member has a depending stub shaft 202 projecting downwardly into a bore 203 in the main shaft 204 and a compression spring 205 abuts at one end upon the bottom of the bore and at its upper end carries a round-headed button 208 abutting upon the lower end of the stub shaft 202. By this means, as will be understood, the driving clutch member 200 and driven clutch member 201 are normally held apart by the spring 205.

The depending tubular guide 208 within which the parts are mounted for rotational and axial movement has on its upper end lafflange 209, and an annular plate 2|0 having a-central perforation 2I| surrounding the shank 20| `is secured to the flange 209 by a circular series of screws 2 I2.

Thus the tubular housing 208 may be supported on the plate 2|0 and the latter upon the driving clutch member 200 when the latter is supported by the shank 20| in a drill press chuck; and the parts within the tubular support 208 may be supported therein as described for the other forms.

The operation of the fonn of Fig. 6 is the same as that of Fig. 4. When the drill press chuck is lowered to apply the tool 8|, the vertical or axial movement of the parts within the tubular support 200 will be guided, partly by the tubular support and partly by the stub shaft 202 telescoped in the bore 203 of the main .shaft 204.

It will be observed that in theform of Figs. 4 and 6 the cylindrical surface of the shaft inside of the helical spring functions to maintain the spring in suitable condition to engage the hollow cylindrical wall of the driven clutch element when the spring is expanded, in a manner similar to that of the sleeve of the form of Fig. 1.

While I-have shown my invention as embodied in three forms, my invention is lnot limited specically thereto. Changes and modifications may be made without departing from the spirit of my invention or sacrificing its advantages, and within the scope of the appended claims.

I claim:

1. In a power transmitting clutch mechanism, a reversible power rotatable driven element, a torque load applying element, a first clutch for receiving power from the driven element and supplying it to the torque load applying element, a second clutch comprising engageable and disengageable clutch elements for respectively receiving power from the driven element and supplying 112 i@ the torque load applying element, the

first clutch being associated with the torque load applying element to drive it and torque loads up to a predetermined maximum, the elements of the second clutch being normally disengaged and automatically engageable to drive the torque load applying element at torque loads above said maximum, and in one direction of rotation of the reversible driven element, means for effecting automatic release of both said clutches at torque loads above a predetermined maximum to stop application of load torque, and a third clutch comprising engageable and disengageable elements for receiving power from the driven element and supplying it to the torque load applying element, the elements of the third clutch being disengaged during rotation of the driven element in said one direction and automatically engageable upon rotation in the other direction to drive the torque load applying element directly.

2. A power transmitting clutch mechanism asv described in claim 1 and in which the said first l clutch has engageable and disengageable elements and one element has a spline connection with the torque load applying'element and is provided with an inclined surface through which it is rotatably driven by the other element of the first clutch and is yieldingly prevented by resilient means from reacting on the inclined surface and being moved thereby out of engagement with the said other element of the first clutch.

3. A power transmitting clutch mechanism as described in claim 1 and in which the said rst clutch comprises engageable and disengageable elements and one element has a spline connection with the torque load applying element and is provided with an inclined surface through which it is rotatably driven by power from the other element of the rst clutch and is yieldingly prevented by resilient means from reacting on the inclined surface and being moved out of engagement with the said other element of the first clutch, and the resilient means comprising a spring, a threaded movable abutment for the spring, and a nut element on the abutment adjustably rotatable, the nut element engaging the said other first clutch element to resiliently exert force thereon.

4. A power transmitting clutch mechanism `as described in claim 12 and in which one of the engageable and disengageable elements of the second clutch is in the form of a helical spring rotatably driven at one end by the said driven element and the other one of said engageable and disengageable elements has a cylindrical bore surrounding and engaged by the outer cylindrical surface of the spring, and the other end of the spring is adapted to transmit its rotary motion to one of the engageablev and disengageable elements of the first clutch through anv inclined surface provided on the other of said engageable and disengageable elements of the first clutch.

5. A power transmitting clutch mechanism as described in claim 12 and in which one of the engageable and disengageable elements of the second clutch is in the form of a helical spring rotatably driven at one end by the driven element and the other of said engageable and disengageable elements has a cylindrical bore surrounding and engaged by the outer cylindrical surface of said spring, and the other end of the spring engages and rotates bodily with one of the engageable and disengageable elements of the first clutch and the said elements 01' the @ist clutch mutually engage on inclined surfaces provided respectively thereon.

6. A power transmitting clutch mechanism as described in claim 1 and in which the engageable and disengageable elements of the third clutch comprise an outer raceway associated with the reversible driven element engaging a plurality of rolling elements and a head element drivingly associated with the torque load applying element and provided with inclined faces wedgingly engageable by the rolling elements upon rotation of the raceway in said other direction to rigidly engage the torque load applying element with the driven element.

7. In a power transmitting clutch mechanism, a power rotatable driven element, a helical spring rotatably drivable at one end by the driven element, a torque load applying element, a clutch element for rotatively driving the torque load applying element having a cylindrical bore surrounding and engageable by the outer generally cylindrical surface of the helical spring, a first intermediate clutch element rotatably drivable by the other end of the spring, jaws on the first intermediate clutch element, a second intermediate clutch element having jaws engageable by the jaws of the first intermediate clutch element, the jaws havinginclined mutually engageable surfaces, and a spline connection between the second intermediate clutch element and the torque load applying element.

8. In a power transmitting clutch mechanism, a reversible power rotatable driven element, a helical spring rotatably drivable at one end by the driven element, a torque load applying element, a clutch element for rotatably driving the torque load applying element having a. cylindrical bore surrounding and engageable by the outer generally cylindrical surface of the helical spring, a first intermediate clutch element rotatably drivable by the other end of the spring, jaws on the first intermediate clutch element, a second intermediate clutch element having jaws engageable by the jaws of the rst intermediate clutch element, the jaws having inclined mutually en-V gageable surfaces, a spline connection between the second intermediate clutch element and the torque load applying element, a frame rotatably supporting the driven element and torque load applying element, the reversible driven element in one direction of rotation effecting driving of the torque load applying element in one direction through the spring and through said intermediate clutch elements, a second clutch comprising a clutch element associated with the torque load applying element and a clutch element associated with the driven element, and automatic means to engage the said second clutch elements upon rotation of the reversible driven element in the other direction to effect driving of the torque load applying element in the other direction.

9. In a power transmitting clutch mechanism, a power rotatable reversible driven element, a helical spring rotatably drivable by one end portion in either direction by the driven element, a torque load applying element having a cylindrical bore and comprising a. coaxial cylinder, respectively on the outside and inside of the helical spring, and respectively engageable by outer and inner cylindrical surfaces of the helical spring upon expansion and contraction thereof respectively, a first intermediate clutch element having jaws thereon and rotatably drivable in either direction by the other end of the spring,

a. second intermediate clutch element having jaws thereon engageable by the jaws of the rst intermediate clutch element to rotatably drive the second intermediate `clutch element in either direction, the jaws having mutually engageable inclined surfaces, and a splinev connection between the second intermediate clutch element and torque load applying element.

10. A power transmitting clutch mechanism as described in claim 9 and in which a spring holds the inclined laces in engagement and permits them to automatically disengage upon attainment of a predetermined driving torque.

1l. A power transmitting clutch mechanism as described in claim 9 and in which the inclined faces for transmitting torque in one direction are of a different inclination from that of the faces for transmitting torque in the other direction and a spring holds the inclined faces in engagement `in either direction and permits them to disengage upon the attainment of predetermined torques in the corresponding direc- 12. In a power transmitting clutch mechanism, a reversible power rotatable driven element, a

. torque load applying element, a rst clutch comthe first clutch being normally engaged and being associated with the torque load applying element to drive it at torque loads up to a predetermined maximum, the elements of the second clutch being normally disengaged and automatically engageable to drive the torque load applying element and loads above said maximum and in one direction of rotation of the reversible driven element, means for effecting automatic disengagement of the said clutch elements at torque loads above a predetermined maximum to stop application of load torque, and a third clutch comprising engageable and disengageable elements for receiving powerfrom the driven element and supplying it to the torque load applying element, the elements of the third clutch being disengaged during rotation of the driven element in said one directionv and automatically engageable upon rotation in the other direction to drive the torque load applying elements directly.

13. In a power transmission clutch mechanism, a helical spring, a torque load applying element having a hollow cylindrical surface engageable by the outer cylindrical surface of the spring upon expansion thereof, an element connected to each end of the spring, one for rotatably supplying power thereto tending to rotate the spring, the other rotatably resisting rotation of the spring and tending to cause it to expand, and a sleeveform liner within the spring'engageable by the convolutions thereof when the spring `is relaxed and supported at each end upon the two said spring-connected elements.

14. A power transmitting clutch mechanism as described in claim 1 and in which the said first clutch has engageable and disengageable elements and one element has a splined connection with the torque load applying element, and is provided with an inclined surface through which'it is rotatably driven by the other element of the first clutch and is yieldingly prevented by resilient means from reacting on the inclined surface and being moved thereby out of engagement with the said one element of the first clutch, and means is provided to adjustably vary the ef' fectiveness of the resilient means to adjustably vary the releasing torque load.

15. A power transmitting clutch mechanism as described in claim 9 and in which a spring holds the inclined faces in engagement and permits them to automatically disengage upon attainment of a predetermined driving torque and meansis provided to vary the electiveness of the spring to vary the predetermined torque.Y

16. In a power operated portable tool, a rear driving member, means for rotating said rear driving member, a front driving member, a driving spring arranged to be actuated by said rear driving member when thel latter is rotated in one direction, a slip connection comprising parts separate from and connected respectively with said spring and said front driving member, said parts having cooperating cam surfaces to cause said front driving member to normally rotate in unison with said rear driving member, one of said parts being yieldable to permit saidI spring and said rear driving member to rotate with relation yto said front driving member when excessive resist-ance is offered to the-movement of the latter, and other means for causing said front driving member to be rotated in a reverse direction.

17. In a power operated portable tool, a rear kdriving member, means for rotating said rearl y driving member, a front driving member, a driving spring arranged to be actuated by said rear driving member when the latter is rotated in one direction, a slipvconnection comprising parts separate from and connected respectively with said spring and said front driving member, said parts having cooperating cam surfaces to cause said front driving member to normally rotate in unison with said rear driving member, one of said parts being yieldable to permit said spring and said rear driving member to rotate with relation to said front driving member when excessive resistance is offered to the movement of the latter, and other means for connecting saidI front drivingv member with said rear driving member when the latter is rotated in a reverse direction.

18. In a self-contained portable tool, a rear driving member, means for rotating the same, a tubular front driving member, means for causing said front driving member to be rotated in a forward direction by said rear driving member, including a part yieldably mounted in said tubular front driving member for axial movement with relation thereto, and held against rotation with relation thereto, and a part connected with said rear driving member for rotation therewith and extending into said tubular front driving member, said parts having means for normally connecting the same for rotation in unison and for disconnecting the same when excessive resistance is oiered to the rotation of said front' driving member, and other means for causing said front drivingmember to be rotated in a reverse direction by' said rear driving member.

19. In a self-contained portable tool, a rear driving member, means for rotating the same, a tubular front driving member, means for causing said front driving member to be rotated in a forward direction by said rear driving member, including a part yieldably mounted in said tubular front driving member for axial movement with relation thereto, and held against rotation with relation thereto, and a part connected with said rear driving member for rotation therewith and extending into said tubular front driving member, said parts having means for normally connecting the same for rotation in unison and for disconnecting the same when excessive resistance is offered to the rotation of said front driving member, and other connecting means interposed between said driving members and so arranged that it will be inoperative when said rear driving member is rotated in a forward direction and will be rendered operative by the rotation of said rear driving member in a reverse direction.

20. In ya self-contained portable tool, a rear driving member, means for rotating the same, a tubular front driving member, means for causing said front driving member to be rotated in a forward direction by said rear driving member, including a part yieldably mounted in said tubular front driving member for axial movement with relation thereto, and held against rotation with relation thereto, and a part connected with said rear driving member for rotation therewith and extending into said tubular front driving member, said parts having means for normally connecting the same for rotation in unison and for disconnecting the same when excessive resistance is offered to the rotation of said front driving member, and a one-way clutch interposed between said driving members to operatively connect the same when said rear driving member is rotated in a reverse direction.

21. In a mechanism of the character described, a rear driving member, a tubular front driving member, means for rotating said rear driving member, a coiled spring arranged within said front driving member and connected with said rear driving member for rotation thereby, a connecting member mounted in said tubular front driving member for yielding movement lengthwise thereof and for rotation therewith, and a shoe rotatably mounted in said front driving member and connected with the front end of said spring for rotation thereby, said shoe and said connecting member having opposed cam surfaces to form a slip connection which will cause the same to rotate normally in unison and will permit said shoe to rotate with relation to said connecting member when excessive resistance is offered to the rotation of said front driving member.

22. In a mechanism of the character described, a rear driving member, means for rotating the same, a tubular front driving member rotatably mounted in alinement with said rear driving member, a spindle rigidly connected with said front driving member and rotatably mounted in said rear driving member and heid against axial movement with relation thereto, a coiled spring mounted in said tubular front driving member and connected'with said rear driving member for rotation thereby, a sleeve mounted about said spindle for movement lengthwise thereof and having guiding contact with the front portion thereof, a spring to move said sleeve rearwardly, a connecting member mounted within said tubular front driving member, held against rotation with relation thereto and connected with' said sleeve for movement therewith lengthwise of said front driving member, and a shoe interposed between said connecting member and said coiled spring and having a part to engage the front end of said coiled spring for rotation thereby, said shoe and said connecting member having opposed cam surfaces to cause said connecting member and said front driving member to normally rotate with said shoe and permit said shoe to rotate with relation to said connecting member when excessive resistance is offered to the rotation of the latter.

23. In a mechanism of the character described, a rear driving member, means for rotating the same, a tubular front driving member having longitudinal .guideways in opposite sides thereof, a part mounted in said front driving member for rotation with relation thereto, said part being connected with said rear driving member for rotation thereby and having on its front face relatively short cam surfaces arranged on opposite sides of its axis, a connecting member mounted in said tubular'front driving member for axial movement with relation thereto and having radial lugs extending into said guideways to cause said front driving member to rotate therewith, said connecting member having 'on its "rear face relatively short cam surfaces in longitudinal alinement with said lugs and adapted to engage the first mentioned cam surfaces, and.

means for yieidingly pressing said connecting member rearwardly and for permitting the same to yield under the pressure of the first mentioned cam surfac when excessive resistance is offered to the rotation of said front driving member, thereby enabling the first mentioned cam l surfaces to ride over the cam surfaces of said connecting member and to successively engage the latter with a series of impacts.

24. In a mechanism of the character described, a rear driving member, means for rotating said driving member, a tubular front driving member, a part rotatably mounted in said tubular front driving member, connected with said rear driving member for rotation thereby and having a plurality of cam surfaces spaced about the axis thereof, a spindle rigidly secured to said front driving member, rotatably mounted in said rear driving member and held against axial movement with relation thereto, an annular connecting member mounted about and guided by said spindle in said front driving member for axial movement with relation thereto, said connecting member having means for causing said front driving member to rotate therewith and having a plurality of cam surfaces spaced about the rear face thereof to cooperate with the first mentioned cam surfaces, and a spring acting on said connecting member to move the same rearwardly and to hold the cam surfaces thereon in operative relation to the first mentioned cam surfaces.

25. In a mechanism of the character described,

a rear driving member, means for rotating the same, a tubular front driving member rotatably mounted in alinement with said rear driving member and having a lateral opening near the front end thereof, a supporting member mounted in said front driving member for movement lengthwise thereof, a spring acting on said supporting member to move the same rearwardly, a shoe rotatably mounted in said front driving member and connected with said rear driving member for rotation thereby, a connecting member mounted about said supporting member for axial movement therewith and held against rotation with relation to said front driving member, a nut threaded onto the front end of said supporting member and having supporting engagement with said connecting member, said shoe and said connecting member having opposed cam surfaces to cause the same to rotate normally in unison and to permit said shoe to rotate with relation to latter in adjusted positions on said supporting' member.

26. In a power operated portable tool, a first driving member, means for rotating said first driving member, a second driving member, a driving spring arranged to be actuated by said first driving member when the latter is rotated in one direction, a slip connection comprising parts separate from and associated respectively with said spring and said second driving member,

said parts having cooperating cam surfaces to cause said second driving member to normally rotate in unison with said nrst driving member, one of said parts being yieldable to permit said spring and said first driving member to rotate with relation to said second driving member when excessive resistance is oiered to the movement of the latter, and other means for causing said second driving member to be rotated in a reverse direction.

27. in a power operated portable tool, a first driving member, means for rotating said lrst driving member, a second driving member, a driving spring arranged to be actuated by said iirst driving member when the latter is rotated in one direction, a slip connection comprisingy parts separate from and associated respectively with said spring and said second driving member, said parts having cooperating cam surfaces to cause said second driving member to normally rotate in unison with said iirst driving member, on-e of said parts being yieldable to permit said spring and said first driving member to rotate with relation to said second driving member when excessive resistance is offered to the movement of the latter, and other means for eiiecting driving of said second driving member by said rst driving member when the latter is rotated 1n a reverse direction.

28. In a self-contained portable tool, a first driving member, means for rotating the same, a tubular second driving member, means for causing said second driving member to be rotated in a forward direction by said rst driving member, including a part yieldably mounted in said tubular second driving member for axial movement with relation thereto, and held against rotation with relation thereto, and a part arranged in driving relation to said rst driving member for rotation therewith and extending into said tubular second driving member, said parts having means to cause said second driving member to normally rotate in unison with said first driving member, and forpermitting driving of said rst driving member without rotation of said second driving member when excessive resistance is ofiered to the rotation of said second driving member, and'other means for causing said second driving member to be rotated in a reverse direction by said iirst driving member.

29. In a self-contained portable tool, a :lirst driving member, means' for rotating the same, a tubular second driving member, means for causving said second driving member to be rotated in with relation thereto, and held against rotation with relation thereto,- and a part arranged in driving relation to said first driving member for rotation therewith and extending into said tubu lar second driving member, said parts having means to cause said second driving member to normally rotate in unison with said iirst driving member, and for permitting driving of said first driving member without rotation oi said second driving member when excessive resistance is offered to the rotation of said second driving member, and other rotary motion transmitting means interposed between said driving'members and so arranged that it will be inoperative when said rst driving member is rotated in a forward direction and will be rendered operative by the rotation of said first driving member in a reverse direction.

30. In a self-contained portable tool, a rst driving member, means for rotating the same, a tubular Asecond driving member, means for causing said second driving member to be rotated in a forward direction by said first driving member, including a part yieldably mounted in said tubular second driving member for axial movement with relation thereto, and held against rotation with relation thereto, and a part arranged in driving relation to said iirst driving member for rotation therewith and extending into said tubular second driving member, said parts having means to cause said second driving member to normally rotate in unison with said first driving member, and for permitting driving of saidv first driving member without rotation of said second driving member when excessive resistance is offered to the rotation' of said second driving member, and a one-way clutch interposed between said driving members to operatively connect the same when said iirst driving member is rotated in a'reverse direction.

31. In a mechanism of the character described, a first driving member, a tubular second driving member, means for rotating said first driving member, a coiled spring arranged within said second driving member and having an end in driving relation with said rst driving member for rotation thereby, a connecting member mounted in said tubular second driving member for yielding movement lengthwise thereof and for rotation therewith, and a `shoe rotatably mounted in said second driving member and connected with the other end of said spring for rotation thereby, said shoe .and said connecting member having opposed cam surfaces to form a slip connection which will cause the same to rotate normally in unison and will permit said shoe to rotate with relation to said connecting member when excessive resistance is oiered to the rotation of said second driving member.

32. In a mechanism of the character described, a iirst driving member, means for rotating the same, a tubular second driving member rotatably mounted in alignment with said rst driving member, a spindle rigidly connected with said second driving member and rotatably mounted in said iirst driving member and held" against axial movement with relation thereto,

a coiled spring mounted in said tubular second driving member and connected with said iirst driving member for rotation thereby, a sleeve mounted about said spindle for movement lengthwise thereof and having guiding contact with the front portion thereof, a spring to move said sleeve rearwardly, a connecting member mounted within said tubular second driving member, held against rotation with relation thereto and connected with said sleeve for movement therewith lengthwise of 'said second driving member. and a shoe interposed between said connecting member and said coiled spring and having a part to engage the front end of said coiled spring for rotation thereby, said shoe and said connecting member having opposed cam surfaces to cause said connecting member and said second driving member to normally rotate with said shoe and permit said shoe to rotate with relation to said connecting member when excessive resistance is offered to the rotation of the latter.

33. In a mechanism of the character described, a first driving member, means for rotating the same, a tubular second driving member having gitudinal alignment with said lugs and adapted to engage the first mentioned cam surfaces, and means for yieldingly pressing said connecting member rearwardly and for permitting the same to yield under the pressure of the first mentioned cam surfaces when excessive resistance is offered to the rotation of said secondfdriving member, thereby enabling the first mentioned cam surfaces to ride over the cam surfaces of said connecting member and to successively engage the latter with a series of impacts.

34. In a mechanism of the character described, a first driving member, means for rotating said driving member, a tubular second driving member, a part rotatably mounted in said tubular second driving member, connected with said first driving member for rotation thereby and having a plurality of cam surfaces spaced about the annoso axis thereof, a spindle rigidly secured to said second driving member, rotatably mounted in said first drivingl member and held against axial movement with relation thereto, an annular connecting member mounted about and guided lby said spindle in said second driving member for axial movement with relation thereto, said connecting member having means for causing said second driving member to rotate therewith and having a plurality of cam surfaces spaced about the rear face thereof to cooperate with the first mentioned cam surfaces, and a spring acting on said connecting member to move the same rearwardly and to hold the cam surfaces thereon in operative relation to the first mentioned cam surfaces.

35. In a mechanism of the character described, a first driving member, means for rotating the same, a tubular second driving member rotatably mounted in alignment with said rst driving member and having a lateral opening near the front end thereof, a supporting member mounted in said second driving4 member for movement lengthwise thereof, a spring acting on said supporting member to move the same rearwardly, a shoe rotatably mounted in said second driving member and connected with said first driving member for rotation thereby. a connecting member mounted about said supporting member for axial movement therewith and held against rotation with relation to said second driving member. a nut threaded onto the front end of said supporting member and having supporting engagement with said connecting member, said shoe and said connecting member having opposed cam surfaces to cause the same to rotate normally in unison and to permit said shoe to rotate with relation to said connecting member when excessive resistance is offered to the rotation of the latter, and a resilient member momted about the exterior of said second driving raam v ber and having a part extending through the opening in said second driving member to engage said nut and hold the latter in adjusted positions on said supporting member.

EDWIN L. CONNELL. 

